In this article, a 4H-SiC metal-insulator-semiconductor-insulator-metal (MISIM) ultraviolet (UV) photodetector (PD) with a normal working temperature up to 550 °C, has been successfully fabricated and characterized for the first time. At 550 °C, the dark current of our fabricated MISIM remains at ~0.2 nA level and a record photo-to-dark current ratio (PDCR) of 62.7 is achieved at a reverse bias voltage of −15 V. Under 275 nm illumination, high responsivity (R) of 0.23 and 0.54 A/W have been achieved at room temperature (RT) and 550 °C, respectively. To the best of our knowledge, this is the best result reported for high-temperature UV detectors based on the 4H-SiC. This work is significant for developing high-temperature 4H-SiC-based UV PDs.

As the p-type doping β-Ga ₂ O ₃ is absent up to now, metal gate (MG) stacks with high work functions are expected to benefit the fabrication of normally-OFF β-Ga ₂ O ₃ transistors. In this article, the electrical characteristics of β-Ga ₂ O ₃ metal-electrode-gated metal-oxide- semiconductor (MOS) devices with Al-rich HfAlO dielectrics and different MG stacks (Ni, Au, Pt, and Ti) are evaluated. The interface state density (Dit) of HfAlO/β-Ga ₂ O ₃ interface is characterized based on the frequency-dependent capacitance-voltage (C-V) and photo-assisted deep ultraviolet (DUV) C-V measurements. An average Dit of 4.45 × 1011 eV ^-1 cm ^-2 is extracted from the photo-assisted (deep UV) C-V measurement, while a large amount of border traps, negative fixed charges, and deep traps is also induced at the oxide layer and/or HfAlO/β-Ga ₂ O ₃ interface. Then, this article investigates the evaluations of Ti, Ni, Au, and Pt as candidate MGs for β-Ga ₂ O ₃ MOS using Al-rich HfAlO as gate dielectric. The obvious flat-band voltage (VFB) shift and gate leakage variation are observed in β-Ga ₂ O ₃ capacitors with different MG solutions, indicating that HfAlO dielectric combined with Ni, Au, and Pt MGs is promising to facilitate some beneficial modifications of normally-OFF β-Ga ₂ O ₃ transistors, while Ti electrode is more suitable for normally-ON β-Ga ₂ O ₃ transistors. This article provides an additional practical guideline for choosing the appropriate MG stacks and potential gate dielectric to the development of normally-OFF Ga ₂ O ₃ transistors.

The damage mechanism of proton irradiation in InP/InGaAs heterostructures was studied. The deep level traps were investigated in detail by deep level transient spectroscopy (DLTS), capacitance–voltage (C–V) measurements and SRIM (the stopping and range of ions in matter, Monte Carlo code) simulation for non-irradiated and 3 MeV proton-irradiated samples at a fluence of 5 × 10¹² p/cm². Compared with non-irradiated samples, a new electron trap at E_C-0.37 eV was measured by DLTS in post-irradiated samples and was found to be closer to the center of the forbidden band. The trap concentration in bulk, the interface trap charge density and the electron capture cross-section were 4 × 10¹⁵ cm⁻³, 1.8 × 10¹² cm⁻², and 9.61 × 10⁻¹⁵ cm², respectively. The deep level trap, acting as a recombination center, resulted in a large recombination current at a lower forward bias and made the forward current increase in InP/InGaAs heterostructures for post-irradiated samples. When the deep level trap parameters were added into the technology computer-aided design (TCAD) simulation tool, the simulation results matched the current–voltage measurements data well, which verifies the validity of the damage mechanism of proton irradiation.

Strains in graphene play a significant role in graphene-based electronics, but many aspects of the grain boundary effects on strained graphene remain unclear. Here, the relationship between grain boundary and strain property of graphene grown by chemical vapor deposition (CVD) on the C-face of SiC substrate has been investigated by Raman spectroscopy. It is shown that abundant boundary-like defects exist in the graphene film and the blue-shifted 2D-band frequency, which results from compressive strain in graphene film, shifts downward linearly as 1/L_a increases. Strain relaxation caused by grain boundary diffusion is considered to be the reason and the mechanism is analyzed in detail.